Full list of all 80 Borderlands Game of the Year Enhanced achievements. It takes around 60-80 hours to unlock all of the achievements on Windows.
Completed each of the larger challenges in all 3 coliseums
Completed the larger challenge in the Hell-Burbia coliseum
Completed the larger challenge in The Angelic Ruins coliseum
Completed the larger challenge in The Gully coliseum
Killed 15 enemies with the Soldier's action skill
Play with at least two other players.
Defeated the Rakk Hive, the Vault Boss, Sledge, Krom, or Flynt in a co-op game
Killed 15 enemies with the Hunter's action skill
Emerged victorious from an arena match
Completed 15 missions in co-op
Rescued a groupmate from death in a co-op game
Won a duel against another player
Won a duel without taking damage
Killed Crawmerax the Invincible
Killed an enemy with the Siren's action skill
Completed all missions in Secret Armory
Completed the lesser challenge in all 3 coliseums
Reached Level 61
Paid for a worthless tour of the world's largest bullet
Killed each of the loot midgets
Reached Level 51
Earned level 50
Destroyed Lance Depot
Rescued Athena
Destroyed a Lancer while in a Racer
Built the New Car: Monster
I bet you never thought you'd be here
Completed the "Braaaaaaaaaaaaains!" mission
Killed Ned. Again.
Killed Ned...sort of
Collected 15 Claptrap bobbleheads
Collected 3 panties, 5 fish in a bag, and 15 pizzas
Found 25 oil cans
Completed the "Jakobs Fodder" mission
Completed the "House of the Ned" mission
Completed a crazy request for Tannis
Killed the Interplanetary Ninja Assassin Claptrap
Killed Commandant Steele-trap
Killed Dr. Ned-trap
Found all 6 Claptrap statues
Killed General Knoxx-trap
Earned level 40
Collected 5 3D glasses
Raced around the Ludicrous Speedway in record time
Killed the Vault Boss
Discovered Eridian Promontory
Discovered Crimson Lance Enclave
Completed all missions in the Rust Commons
Rescued enough Claptraps to earn 42 inventory slots
Killed Flynt
Killed the Rakk Hive
Discovered Trash Coast
Earned $1,000,000
Killed an enemy plumber-style
Earned level 30
Reached proficiency level 10 with any weapon type
Killed Krom
Killed 25 enemies with shock weapons
Discovered Krom's Canyon
Killed 25 enemies with corrosive weapons
Discovered The Scrapyard
Completed 5 missions in the Rust Commons
Completed all missions in the Arid Badlands
Earned level 20
Equipped a class mod for your character
Killed Sledge
Discovered Headstone Mine
Sold 50 guns to a shop
Applied an elemental artifact
Mastered the technology of Pandora
Killed 25 enemies with explosive weapons
Killed 25 enemies by ramming them with any vehicle
Discovered Sledge's Safe House
Earned level 10
Killed 15 enemies with the Berserker's action skill
Killed 25 enemies with incendiary weapons
Killed 5 Rakk in under 10 seconds
Earned level 5
Discovered Skag Gully
Completed 5 missions in the Arid Badlands